Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > P2- Topic 6- Inheritance, Variation and Evoloution > Flashcards

P2- Topic 6- Inheritance, Variation and Evoloution Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is sexual reproduction? 3

A

Type of reproduction

the joining of male and female gametes, each containing genetic information from the mother or father.

Sperm and egg cells in animals

Pollen and egg cells in flowering plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are gametes?2

A

Sex cells (sperm cells and egg cells in
animals, pollen and egg cells in flowering
plants).

● Haploid (half the number of chromosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what does meiosis lead to 3

A

formation of four non-identical cells from one cell

Chromosome number is halved.

Involves two divisions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is asexual reproduction?

A

Involves mitosis only.

Produces genetically identical offspring
known as daughter cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what happens in meiosis 4

A

a cell divides to form gametes

copies genetic information

cell divides 2x to form four gametes, each with a single set of
chromosomes

all gametes are genetically different from each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is meiosis important for sexual

reproduction? (2)

A

increases genetic variation.

ensures the zygote formed at fertilisation is diploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe fertilisation and its resulting

outcome 2

A

Gametes join together to restore the normal
number of chromosomes and the new cell then
divides by mitosis (which increases the number
of cells).

As the embryo develops, cells differentiate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the advantage of sexual

reproduction?3

A

-produces variation in the offspring

-if the environment changes variation gives a survival advantage by natural
selection

• natural selection can be speeded up by humans in selective breeding to
increase food production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the disadvantages of sexual

reproduction (3)

A

o parents are required.

-reproduction
difficult in endangered populations or in species which
exhibit solitary lifestyles

-More time and energy is required so fewer offspring
are produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the advantages of asexual

reproduction (4)

A

only one parent needed

  • more time and energy efficient as do not need to find a mate
  • faster than sexual reproduction
  • many identical offspring can be produced when conditions are favourable.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the disadvantage of asexual

reproduction?2

A

No genetic variation (except from
spontaneous mutations)

reducing the
probability of a species being able to
adapt to environmental change.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the circumstances in which fungi reproduce sexually and asexually 2

A

Asexual reproduction by spores.

Sexual reproduction to give variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the circumstances in which Malarial parasites reproduce sexually
and asexually 2

A

Sexual reproduction in the mosquito.

Asexual reproduction in the human host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the circumstances in which plants

reproduce sexually and asexually

A

Sexual reproduction to produce seeds.

Asexual reproduction by runners (e.g.
strawberry plants) or bulb division (e.g.
daffodils).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is understanding the human genome

important?4

A

The whole human genome has been studied and is
important for the development of medicine in the future

search for genes linked to different types of disease

  • understanding and treatment of inherited disorders
  • use in tracing human migration patterns from the past
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define genome

A

The entire genetic material of an organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the structure of DNA

A
  • polymer
  • made up of two strands
  • forming a double
    helix.
  • DNA contained in structures called chromosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are DNA nucleotides made up of?3

A

common sugar

phosphate group

one of four different bases attached to the sugar. A,T,C,G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Define gene

A

-a small section of DNA on a chromosome.

Each gene codes
for a particular sequence of amino acids, to make a specific protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the monomers of DNA?

A

Nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q 
Describe how nucleotides interact to form a molecule
of DNA (3)
A

Sugar and phosphate molecules join to form a
sugar-phosphate backbone in each DNA strand.

Base connected to each sugar.

Complementary base pairs (A pairs with T, C pairs with G)
joined by weak hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Explain how a gene codes for a protein 3

A

A sequence of three bases in a gene forms a triplet.

● Each triplet codes for an amino acid.

● The order of amino acids determines the structure
(i.e. how it will fold) and function of protein formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is protein synthesis?

A

The formation of a protein from a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the two stages of protein synthesis?

A
  1. Transcription

2. Translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What does transcription involve?

A

The formation of mRNA from a DNA

template

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Outline transcription 4

A
  1. DNA cannot move out of
    the nucleus as it is too big.
  2. The two strands pull apart from each other, and mRNA nucleotides
    match to their
    complementary base on the strand.
  3. mRNA nucleotides joined together, creating a new
    strand called the mRNA strand. This is a template of the original DNA.
  4. The mRNA then moves out of the nucleus to the cytoplasm and onto
    structures called ribosomes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what does translation involve

A

ribosome joins in a specific order dictated by the mrRNA to form a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

outline translation 4

A
  1. mRNA attaches to a ribosome.
  2. Ribosome reads the mRNA bases in triplets. Each triplet codes
    for one amino acid which is brought to the ribosome by a tRNA molecule (carrier molecule).
  3. A polypeptide chain is formed from the sequence of amino
    acids which join togethe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is a mutation? 2

A

A random change in the base sequence of DNA

results in no change to the protein coded for, or
genetic variants of the protein (slight alteration but
appearance and function remain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe the effect of a gene mutation in coding DNA 2

A

the protein structure and function may change (an enzyme may no longer
fit its substrate binding site or a structural protein may lose its
strength).

● If a mutation does not change amino acid sequence, there is no effect on protein structure or function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is non-coding DNA?

A

DNA which does not code for a protein but controls which genes are expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe the effect of a gene mutation in non-coding

DNA (2)

A

Gene expression may be altered, affecting protein production and the resulting phenotype (physical charecteristics)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are alleles?

A

Different versions of the same gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is a dominant allele?

A

A version of a gene where only one copy is needed for it to be expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is a recessive allele?

A

A version of a gene where two copies are needed for it to be expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is meant when an organism is homozygous?

A

When an organism has two copies of the same allele (two recessive or two
dominant)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is meant when an organism is heterozygous?

A

When an organism has two different versions of the same gene (one dominant and one recessive).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the genotype? and example 2

A

The genes present for a trait

The combination of alleles an individual has, e.g. Aa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the phenotype? and example 2

A

The visible characteristic eye colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the problem with single gene crosses?

A

Most characteristics are controlled by

multiple alleles rather than just one.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Give 2 examples of inherited disorders and allele cause

A

Polydactyly (having extra fingers or toes)

dominant allele.

Cystic fibrosis (a disorder of cell membranes

recessive allele.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How are embryos screened for inherited disorders? 3

A

In IVF, one cell is removed (from an 8 cell embryo)

tested for disorder-causing
allele

If the cell doesn’t have any indicator alleles, then the originating embryo is
implanted into the uterus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are the ethical issues concerning embryo screening?3

A

● It could lead to beliefs in society that being disabled or having a disorder is less human or associated with inferiority.

● The destruction of embryos with inherited disorders is seen by
as murder as these would go on to become human beings.

● concept of designer babies= parents convenience or wishes than the child’s wellbeing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are the economic issues

concerning embryo screening?1

A

Costs of hospital treatment and medication considered if it is known that a child will have an inherited disorder and financial support explored if necessary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are the social issues concerning

embryo screening?

A

● Social care for children with inherited disorders may
need to be considered if parents are unable to provide care.

● If an embryo is found to have an inherited disorder and is terminated, this can prevent a child and its parents from potential suffering in the future due to the disorder

46
Q

What are the ethical concerning gene therapy

A

● believe that it is going
against and ‘playing God’.

● The introduced genes could enter sex cells and so be passed to future generations

47
Q

What is variation?

A

Differences in the characteristics of
individuals in a population is called
variation

48
Q

What are the causes of variation within a species? 3

A

-Genetics
● Environment
● A mixture of both of the above weight

49
Q

What is genetic variation

A

● Variations in the genotypes of organisms of
the same species due to the presence of
different alleles.

● Creates differences in phenotypes

50
Q

What creates genetic variation in a species?2

A

● Spontaneous mutations

● Sexual reproduction

51
Q

What is the consequence of a new phenotype caused by a mutation being suited to an
environmental change?

A

There will be a rapid change in the

species.

52
Q

How may a gene mutation affect an organism’s

phenotype? (3)

A

No effect on phenotype.

some influence phenotype, change in eye colour

may determine phenotype by completely changing the sequence of amino acids.

53
Q

What is evolution?2

A

change in the inherited characteristics of a population over time

by natural selection resulting in the formation of a new species

54
Q

Outline the theory of natural selection 6

A
  1. Genetic variation by mutations.
  2. Selection pressures (e.g. competition, disease) exist.
  3. Random mutation gives an organism a selective advantage.
  4. Organism is better adapted to the environment and survives.
  5. Organism reproduces, passing on its beneficial alleles.
  6. Frequency of advantageous alleles increase
55
Q

How do two populations become different species?

A

When their phenotypes become different to the extent that they can no longer interbreed to produce fertile offspring.

56
Q

What is selective breeding?

A

humans

breed plants and animals for particular genetic characteristics

57
Q

Outline the main steps involved in selective breeding 4

A
  1. Identify a desired characteristic e.g. disease resistance.
  2. Select parent organisms that show the desired traits and breed them together.
  3. Select offspring with the desired traits and breed them together.
  4. Process repeated until all offspring have the desired traits
58
Q

Give examples of characteristics selected for selective breeding.4

A

Disease resistance in food crops.

• Animals which produce more meat or milk.

• Domestic dogs with a
gentle nature.

• Large or unusual flowers

59
Q

What is the main advantage of selective breeding?4

A

Creates organisms with desirable features:

● Crops produce a higher yield of grain
● Cows produce a greater supply of milk
● Plants produce larger fruit
● Domesticated animals

60
Q

Outline the disadvantages of selective

breeding (4)

A
  • Reduction in the gene pool (which becomes especially
    harmful if sudden environmental change occurs).

● Inbreeding results in genetic disorders.

● Development of other physical problems e.g. respiratory problems in bulldogs.

● Potential to unknowingly select harmful recessive alleles.

61
Q

What is genetic engineering?

A

modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

62
Q

examples of genetic engineering in bacteria cells and plants 3

A

● Disease resistance
● Produce larger fruits
To produce human insulin to treat diabetes mellitus

63
Q

Describe the benefits of genetic engineering (3

A

-Increased crop yields for growing population e.g.
herbicide-resistance, disease-resistance.

● Useful in medicine e.g. insulin-producing bacteria, anti-thrombin in goat milk, possibility to overcome some inherited disordersproducing human insulin

● GM crops produce scarce resources e.g. GM golden rice produces beta-carotene (source of vitamin A in the body)

64
Q

Describe the risks of genetic engineering

(4

A

● Long-term effects of eatingGM crops unknown.

● Negative environmental impacts e.g. reduction in biodiversity, impact
on food chain, contamination of non-GM crops forming ‘superweeds’.

● health problems in GM animals.

● GM seeds are expensive

65
Q

How is genetic engineering used to
protect crops against insects?
2

A

The gene for toxin production in Bt can be isolated and inserted into the DNA of crops.
● Bt crops now secrete the toxin which kills any insect larvae that feed on it

66
Q

Describe the process of genetic

engineering 5

A

enzymes are used to isolate the required gene

gene is inserted into a vector(bacterial plasmid,virus)

vector is used to insert the gene into the required cells

at an early stage of development genes are transferred to the cells of animals, plants or microorganisms so that they develop with desired characteristic

67
Q

What is a vector?

A

A structure that delivers the desired gene
into the recipient cell e.g. plasmids,
viruses.

something that transmits (carries) something else.

68
Q

explain genetic enginerring to produce human insulin?4

A
  • human insulin gene is removed using a restriction enzyme.
  • vector- bacterial plasmid is cut open using the same restriction enzyme to create sticky ends

-Ligase enzymes join the sticky ends of the DNA and vector DNA
forming recombinant DNA

-Recombinant DNA mixed with and ‘taken up’ by target cells.

69
Q

How can plants be cloned? (2)

A

● Taking plant cuttings

● Tissue culture

70
Q

What is tissue culture?

A

Using small groups of cells from part of a

plant to grow identical new plants.

71
Q

Describe how plants are grown using

tissue culture 4

A
  1. Select a plant that shows desired characteristics.
  2. Cut multiple small sample pieces from meristem tissue.
  3. Grow in a petri dish containing growth medium.
  4. Transfer to compost for further growth.
72
Q

What must be ensured when preparing tissue cultures?

A

Ensure aseptic conditions to prevent

contamination by microorganisms.

73
Q

What does the growth medium contain?

A

Nutrients and growth hormones

74
Q

What are the advantages of growing

plants by tissue culture? (3)

A

● Fast and simple process.
● Requires little space.
● Enables the growth of many plant clones with the same
desirable characteristics.
● Useful in the preservation of endangered plant species

75
Q

What are the disadvantages of growing plants by tissue culture? (2)

A

● Reduction in the gene pool.
● Plant clones often have a low survival rate.
● Could unknowingly increase the presence of harmful recessive alleles.

76
Q

Describe the plant cuttings method of plant cloning

A

Older but simpler method than tissue culture.
Gardeners use this method to produce many
identical new plants from a parent plant.

77
Q

Detail the process of the plant cuttings

method of plant cloning 4

A
  1. cuttins taken from parent plant.
  2. lower leaves of the branch are removed and the stem is planted.
  3. Plant hormones are used to encourage new root development. compost
  4. A plastic bag is used to cover the new plant to keep it warm and
    moist.
  5. New roots and a new plant is formed after a few week
78
Q

What does embryo transplanting involve?5

A

an embryo is removed from its mother’s uterus before its cells have begun to specialise

female inseminated

embryo is then split, creating a large number of identical embryos.

embryos inserted into host mothers

embryos’ cells become specialised in the host mothers and they develop into new organisms.

host mothers give birth to offspring identical to each other (clones).

79
Q

Describe how adult cell cloning is performed 4

A

∙nucleus is removed from an unfertilised egg cell.

  • nucleus from an adult body cell is inserted into the egg cell.
  • electric shock stimulates the egg cell to divide to form an embryo.
  • embryo cells has the same genetic information as the adult skin cell.
  • When embryo has developed it is inserted into the womb of an adult female to continue its development.
80
Q

Outline the theory of evolution by natural selection.

3

A

Individuals of a species show a wide range of variation for a characteristic.

Those with the characteristic most suited to the environment will survive breed most successfully.

The desirable and useful characteristic passed onto their offspring

81
Q

Why was Darwin’s theory of evolution

not accepted initially? 3

A

● Most people believed in creationism
● Insufficient evidence to prove the theory
● variation and inheritancewas not known at the time

82
Q

What was Jean-Baptiste Lamarck’s

theory of inheritance and example 2

A

That changes during the lifetime of an
organism can be inherited.

giraffe that stretches its neck a lot to reach the leaves on the tallest trees may develop a long neck

83
Q

Outline the process of speciation through geographic isolation.
4

A

● Two populations of the same species are separated geographically

● Geographic isolation prevents interbreeding and mixing of genes
between the populations.

● Due to different selection pressures, different mutations occur producing different phenotypes in each population
.
● Over time, the two populations may evolve so that they are not able to
interbreed

84
Q

Why is genetic variation important in speciation

A

produces phenotypic variation, some of which are better suited to the environment and are selected for

85
Q

what is alfred wallace known for

A

independently proposed the theory of evolution by natural selection

86
Q

How did Mendel study inheritance?2

A

carry breeding experiments on
plants (peaplants)

analysing the ratio of characteristics in offspring

87
Q

Why was Mendel’s work not recognised

until after his death?2

A

didn’t explain the mechanism of inheritance, as chromosomes were only discovered after his death.

not published in a reputable scientific journal.

88
Q

State two kinds of evidence used to show evolution

A

● Fossils

● Antibiotic resistance in bacteria

89
Q

How are fossils formed?3

A

-when parts of organisms don’t decay as
one or more of the conditions needed for decay are absent h20,oxygen

• when hard parts of the organism are replaced by minerals

• when organisms leave traces on the earth, which are then preserved in rock as footprints, burrows and
rootlet trace

90
Q

Why are there few traces of early life-forms left behind?

A

They are mostly soft-bodied

geological events volcanoes

91
Q

How do fossils act as evidence for evolution?

2

A

can identify the ages of the fossils and use them to show how organisms change over time

92
Q

What do branches in evolutionary trees

indicate?2

A

Where speciation has occurred

common ancestor and ancestral species

93
Q

State the factors that may lead to extinctions. 4/5

A 
● New disease
● Predation
● Competition
● Changes to the environment
● Catastrophic events
94
Q

What enables bacteria to evolve quickly?

A

The fast rate of their reproduction

95
Q

Outline the process of antibiotic

resistance bacteria evolving.4

A

● Mutations occur in bacteria producing genetic variation.

● Certain strains are resistant to antibiotics and are not killed when the antibiotic is applied.

● Resistant strains survive and reproduce..
● Over time, the population of the resistant strains increase

96
Q

Why are resistant strains of bacteria dangerous?

A

People have no immunity to them and

there is no effective treatment

97
Q

State an example of a resistant strain of bacteria.

A

MRSA

98
Q

What can be done to reduce the rate of
development of antibiotic resistant
bacteria?3

A

● Refrain from inappropriately prescribing
antibiotics eg. for viral diseases.
● Patients should complete the prescribed course of antibiotics.
● Restrict agricultural uses of antibiotics

99
Q

Why is it difficult to keep up with

emerging resistance strains?

A

Developing antibiotics have a high cost

and take a long time to develop

100
Q

By what process do bacteria develop resistance to antibiotics 2

A

natural selection” or “mutation

101
Q

What are the classes of organisms as

determined by Carl Linnaeus? 7

A 
Kingdom
phylum
class
order
family
genus
species
102
Q

Which features are living creatures traditionally classified by?

A

By their structure and characteristics

genus and species.

103
Q

What is the binomial system of naming

organisms?

A

Genus name followed by species name

104
Q

Why were new classification models

proposed?2

A

● Improved microscopes have allowed scientists to see more detailed internal structures of different organisms

● Improvement in understanding of
biochemical processes.

105
Q

State the three domains. Carl Woese 3

A

● Archaea
● Eukarya
● Bacteria

106
Q

Which organisms belong in the domain

Archaea?

A

primitive bacteria usually living in extreme environments)

107
Q

Which organisms belong in the domain

Bacteria?

A

true bacteria)

108
Q

Which kingdoms belong in domain

Eukarya?

A

● Plants
● Animals
● Fungi
● Protists

109
Q

How are evolutionary trees created?

A

examining the DNA of different
species and analysing how similar the
sequences are

110
Q

What kingdom does Homo sapiens belong to?

A

“animals” or “animalia” or “animal kingdom”

111
Q

How many kingdoms are there?5

A 
animal,
plant,
fungi
protist
bacteria

Biology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions